The Revolution That Should Have Been — and Still Could Be | Conjecture Institute

Image by Amaro KoberleYour browser does not support the audio element.<br>“Paul’s theory is the single most important discovery in quantum foundations so far in the twenty-first century,” says Gilles Brassard FRS, co-inventor of quantum cryptography and quantum teleportation and recipient of the Wolf Prize, Breakthrough Prize, and Turing Award.<br>It is poetic justice that the mathematician under whom Conjecture Institute Fellow Paul Raymond-Robichaud began his PhD and learned mathematics, Gert Sabidussi, was a colleague of Albert Einstein at the Institute for Advanced Study in Princeton, New Jersey. The greatest physicist of the twentieth century famously opposed quantum mechanics twice over: he refused to accept a random world (“God does not play dice”), nor one that allowed for so-called “spooky action at a distance.” He thought that quantum physics could not possibly be complete, that some deeper, complete theory would recover a deterministic and local universe. The debate over local-realism—the philosophical position that the universe is made of real systems with real properties, and that those properties can only be influenced by nearby events noninstantaneously—has dominated the foundations of physics community for about a century.<br>At long last, Paul has vindicated Einstein’s dream.<br>Paul’s work should have ended the debate in favor of local-realism. The countless hours and hundreds of millions of dollars (possibly billions, depending on how you count) that go into ‘nonlocal’ research should have been redirected by now.<br>But the world has not yet heard of Paul’s work. The foundations of physics community is still arguing about what should be a settled matter, like post-Darwinian biologists still arguing over whether or not species share a common ancestor.<br>Conjecture Institute exists to change that.<br>Constraints, Shallow and Deep<br>One of the most well-known applications of scientific theories is the derivation of predictions: the scientific community was amazed at Newton’s ability to predict the trajectories of the planets from the foundational tenets of his theory, for example. Such a result gives us the specific data about certain systems ‘for free’—they follow from direct application of the theory.<br>Less well-known is the rare but beautiful derivation of a universal statement from a theory’s core tenets. For example, one can prove from quantum computation that it is impossible (always and everywhere) to copy an unknown quantum state from one medium to another. This sort of result, deeper than the trajectories of the planets, tells us about the kinds of things we can and cannot do to any quantum mechanical system. We will immediately know ‘for free’ that, if a system is described by quantum mechanics, then it obeys this so-called no-cloning theorem.<br>And even less well-known, rarer, yet deeper than that is the discovery of an extremely general result that does not give us data about a particular system, nor even the kinds of things we can do to systems that obey a particular theory. The result I am referring to is a theorem that has the logic of a theory of theories—it gives us constraints that all theories, both known and unknown, must conform to. For example, the principle of conservation of energy is thought to be respected both by accepted theories like quantum mechanics and general relativity, but also by their eventual successors.<br>Conjecture Institute Fellow Paul Raymond-Robichaud discovered precisely such a constraint—under extremely general assumptions that we will review, all theories, both known and unknown, are expressible in entirely local terms. Spooky action at a distance and all other forms of apparently nonlocal action in the universe are just illusions or relics of how we express our theories. And, as we will see, Paul’s work did more than ‘just’ constrain all theories in physics that satisfy very general criteria—he showed how to find the underlying local reality behind such theories.<br>In a single stroke of mathematics, Paul should have put to bed all debates having to do with whether or not physics is local, and all lines of thought that insist on nonlocality. And yet there continue to be entire research groups dedicated to subjects such as ‘quantum nonlocality’ and entire careers dedicated to proposed theories of quantum gravity that presume nonlocality.<br>The Era-Defining Debate in Quantum Foundations<br>The debate began, not over locality, but over determinism and quantum theory’s completeness. At the famous Solvay Conference in 1927, Albert Einstein argued to the other founders of quantum mechanics that quantum mechanics must have been logically and physically inconsistent. Einstein thought that the theory as it was currently constituted implied a nondeterministic universe, and he refused to accept such a world. The titan of science would present thought experiments to his colleagues at breakfast that he had hoped...